1. Field of the Invention
The present invention relates to a sleeve member for enclosing an amputation stump, preferably to a cushioned sock for use by, e.g., below-knee (BK) amputees. The sleeve member is provided in a contoured form fit configuration which adapts to a right or left side bias of the bony prominence of the residuum (stump). Cushioning material may optionally be provided on the inside and/or outside of the sleeve to minimize the discomfort of a prosthetic device, such as an artificial arm or leg. In a preferred embodiment, the cushioning material is in a recessed achilles configuration: the cushioning material does not contact the wearer at an upper posterior ( i.e., knee crease), or upper anterior (i.e. elbow crease, etc.) portion of the residuum.
2. Discussion of the Background
For at least the past 80 years amputees have worn tubular socks over their residual limb. Cotton, wool and cotton-wool blends have typically been used. More recently, with the advent of synthetic materials, nylon and other textiles, including some with a measure of elasticity, have also been utilized.
In a typical below-knee (BK) prosthesis an amputee's stump tends to "piston" in the socket: during ambulation the stump will come up in the socket of the prosthesis until the attaching means holding the prosthesis to the wearer cause the prosthesis to lift with the stump. On the way down, air may be trapped between the residuum and stump sock, or between the prosthesis socket and sock, or between a socket liner and a sock.
With wool and cotton socks which tend to breathe and which are not airtight this pistoning effect is not a major problem with regard to the generation of sound effects. Since wool and cotton tend not to tightly form fit a residuum, however, the amputee typically packs a material around the residuum once it is placed into the prosthetic device or adds additional socks to increase thickness or puts on thicker socks in order to provide necessary fit. However, for socks which do not breathe and which are made from, e.g., polymeric material, a problem occurs when the residuum pistons in the prosthetic device: terrific sound effects such as sucking and gurgling noises are generated which are obtrusive and inappropriate, often embarrassing the wearer. In addition, such air pockets produce non-uniform pressures and loading discontinuities on the skin, irritating it.
Finally, many amputees experience a swelling of the stump. When the residuum is in a prosthetic socket the stump tends to contract significantly, and when taken out of the socket the stump tends to expand within minutes of removal. This expansion and contraction of the residuum contributes to the development of air pockets and the generation of obtrusive noises since a sock which may have provided a comfortable fit on the expanded stump becomes a loose fit with air pocket opportunities when the residuum is placed inside the prosthetic socket. In addition, and over time, an amputee's residuum tends to adjust in size, usually shrinking. As these changes occur they increase the tendency for the pistoning effect, described above, to occur. In addition to the embarrassment caused by the sound effects generated by pistoning, cushioned socks which allow or promote air pocket formation quickly wear out and, if not replaced often, lead to lesions, etc. on the residuum.
Currently available cushioned residuum socks are tubular or conical and do not provide a form fit on an amputee's residuum. Regardless whether such socks are provided with internal and/or external cushioning material they fail to avoid air pockets. While a stump may generally have a roughly conical or cubical shape there are invariably recessed areas on, e.g., the medial side of the prominent tibia bone. Generally, on a below knee, left side residual limb the recessed area will be predominantly on the right side of the tibia bone. There is also typically a smaller recessed area on the left side. For right side residual limbs the predominant recessed area is on the left side of the bone, with smaller recessed areas on the right side. Usually the greatest recess occurs immediately below the patella, on either side. In addition, left side amputees typically have a right side bias to the bony prominence of the below knee stump, and right side amputees have a similar bias to the left side. Conventional tubular or conical elastic socks simply cannot account for these several variable conditions without using extremely high levels of elastic tension which compress the outer-most points along the stump's circumference, causing discomfort and a non-uniform fit.